1. Field of the Invention
This invention relates to copolymers based on vinyl acetate and methyl acrylate produced by copolymerization followed by partial saponification while dissolving the copolymer in an alkali base.
2. Description of the Prior Art
It is known that vinyl acetate and methylacrylate can be polymerized in aqueous emulsion by addition of polymerization initiators and emulsion agents at increased temperatures such as 50.degree. C. to 80.degree. C. Other monomers such as acrylic acid may also be used. Copolymer dispersions are obtained which, depending upon their composition, can be used as paint, wood adhesive or additives for hydraulic binders. Such copolymers, as aqueous emulsions, are relatively easily saponified causing a detrimental effect when used as additives in hydraulic binders such as cement. The saponification of polyvinyl acetate dispersions results in aqueous solutions of polyvinyl alcohol and/or partially saponified products which may be used as protective colloids particularly in the emulsion polymerization of vinyl acetate. They do not have a delaying effect upon the emulsion polymerization.